1. Field of the Invention
Embodiments of the present invention relate to low profile USB device and in particular to a USB device formed as a SIP module.
2. Description of the Related Art
The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large storage capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
Equally ubiquitous is the universal serial bus (USB) interface for transferring signals between devices such as those named above and other components such as for example desktop computers and the like. A typical USB storage device includes a memory portion coupled to a USB connector capable of mating within a USB slot of a host device. The memory portion typically includes a printed circuit board on which are mounted one or more flash memory chips, a controller, passive components and an LED for indicating when the memory is being accessed. While there are several types of USB connectors, the most commonly used is the type-A plug on which is a 4-pin connector, surrounded by a shield. A conventional type-A USB plug includes a base on which is formed a signal power pin, a pair of signal pins and a signal ground pin. During a conventional fabrication process, the USB connector may be affixed to the memory portion, as by welding and/or soldering, and the memory portion and connector may then be covered by the shield.
When fabricating the memory portion of conventional USB memory device, TSOP memory and/or controller packages are surface mounted to the printed circuit board. After this step, the memory portion is then typically encased within a molding compound of epoxy resin in an overmolding process to seal and protect the memory portion. Examples of USB devices formed in this way using TSOP packages are disclosed for example in U.S. Patent Application Publication No. US 2006/0184709, entitled, “USB Memory Storage Apparatus,” and U.S. Pat. No. 7,249,978, entitled, “Reduced-Length, Low-Profile USB Device and Card-Like Carrier.” USB memory devices such as those described above have a large thickness owing to the fact that, with the TSOP packages, the devices include an overmolded package mounted within an overmolded package.